As a general rule, either substantive dyes or oxidation dyes may be used for coloring keratinic fibers. Although intense colors with good fastness properties may be obtained with oxidation dyes, the development of the color generally takes place under the influence of oxidizing agents such as H2O2, for example, which in some cases may result in damage to the fiber. Furthermore, some oxidation dye precursors or certain mixtures of oxidation dye precursors may have a sensitizing effect on people with sensitive skin. Substantive dyes are applied under gentler conditions. The disadvantage of these dyes, however, lies in the fact that the colors often have inadequate fastness properties, in particular with regard to hair washing, but also with respect to external influences, such as sunlight, or reactive environmental chemicals, such as, for example, swimming pool water.
For temporary colors, coloring or tinting agents may be used which include substantive dyes as the coloring component. These are dye molecules which attach directly to the hair and do not require an oxidative process to develop the color. These colors are generally significantly more sensitive to shampooing than oxidative colors, such that an often undesired shift in shade or even a visible “decolorization” occurs much more quickly.
Achieving a uniform coloring of hair that has been frequently treated, such as for example bleached or permanently waved hair, where the fibers present differing degrees of pre-existing damage in the various lengths or variously treated areas, represents a particular challenge in terms of coloring hair with substantive dyes. During the coloring process itself, the coloring agent may exhibit uneven coloring on hair with differing degrees of pre-existing damage, while repeated hair washing may also cause the dyes to be washed out of the different areas of the hair to varying degrees, resulting in an inconsistent, and hence undesirable, color result.
In the development of coloring products based on substantive dyes, there is still a particular focus on producing dye formulations having reduced selectivity, meaning that a uniform color result may be achieved on sections of the hair that have varying degrees of pre-existing damage. In particular, this reduced selectivity should remain present not only immediately after the coloring process but also after repeated hair washes.
Formulations including surfactants are often used for coloring keratinic fibers. The use of surfactants has the disadvantage that too great a degreasing of the scalp may occur during the hair coloring process, leading to an itchy scalp or to the formation of dandruff. Oil-replenishing substances which preserve the lipid content of the scalp may be used in the hair coloring formulations to protect the scalp. However, oil-replenishing substances which have a positive effect on the scalp may lead to a negative effect on the hair fiber, since the oil-replenishing substances cause the hair to appear greasy too quickly, giving an unkempt and unattractive appearance to the hairstyle. Despite the large number of active ingredients that are now known in the industry, there is therefore still a need for substances or combinations of substances which protect the scalp during the coloring process and give the hair shine, without making it appear prematurely greasy.
In addition, the use of some active ingredients may be incompatible with the dyes that are used, such that the color result obtained with a combination of an active ingredient and dye is poorer than that obtained with the dye alone. There is, therefore, a need for suitable combinations of active ingredients and dyes, in which the positive effect of the active ingredient may develop without also having a disadvantageous effect on the fastness properties of the dye.
An object of the present specification is therefore to provide a coloring agent for keratinic fibers, in particular human hair, which, in addition to other positive fastness properties, has a low selectivity (or a good equalizing capacity) and good wash fastness. At the same time, the scalp should be protected during the coloring process and a shine should be imparted to the keratinic fibers, without however making them appear prematurely greasy.
The use of cationic anthraquinone dyes in products for coloring keratinic fibers is already known in principle from the prior art, for example from EP 1 006 154 B1 or EP 1 820 826 A1. Furthermore, combinations of cationic anthraquinone dyes with oxidation dye precursors of the developer type are claimed in EP 2 329 809 for the oxidative coloring of hair.
Combinations of cationic anthraquinones with special fatty acid diesters of an alkanediol have not yet been described. During the course of the work leading to the agents of this disclosure, it was surprisingly found that these combinations lead to colors which achieve the above object to an outstanding degree.
Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with this background of the invention.